1. Field of the Invention
The present invention relates generally to an internal cylinder intake-air quantity calculating apparatus and method for a variable valve open/closure timing controlled internal combustion engine in which open and closure timings of intake and exhaust valves are arbitrarily controlled. The present invention, more particularly, relates to the internal cylinder intake-air quantity calculating apparatus and method which accurately calculate a cylinder intake-air quantity sucked into each one of a plurality of engine cylinders (hereinafter referred to as an internal cylinder intake-air quantity) on the basis of an output of an airflow meter installed on a portion of an intake-air passage which is located at an upstream of an intake manifold.
2. Description of the Related Art
A Japanese Patent Application First Publication No. Showa 61-258942 published on Nov. 17, 1986 exemplifies a previously proposed fuel injection controlling apparatus in which a weight mean is carried out for the intake-air quantity measured by means of an airflow meter to calculate the internal cylinder intake-air quantity in a first-lag order relationship in order to cope with a stepwise change in an opening angle of an engine throttle valve in a normally available internal combustion engine in which an opening angle of the throttle valve is controlled to adjust the intake-air quantity supplied to the engine.